Bob Perry, the 80-year-old billionaire who founded Perry Homes, gave $1 million to Freedom Fund North America on Oct. 16, according to a filing the organization made with the Federal Election Commission on Wednesday. The donation came just a day after the organization was formed.

Because the group said it did not receive Perry's donation before Oct. 17, it was able to keep his identity secret until far past Election Day. Washington, D.C. lawyer Michael Adams served as the group's treasurer.

Freedom Fund North America spent $990,000 on advertisements opposing Democrats Sen. Jon Tester in Montana and Heidi Heitkamp in North Dakota as well as an ad in support of Heitkamp's opponent, Rep. Rick Berg (R). Both Tester and Heitkamp won their races.

Perry was the top super PAC contributor in the nation as of September, according to ProPublica. Perry gave at total of $10 million to Restore Our Future, the super PAC backing former Republican presidential candidate Mitt Romney. He's most famous for being the largest single donor to Swift Boat Veterans for Truth, a tax-exempt group which attacked Democratic Presidential Candidate John Kerry's service in Vietnam during the 2004 presidential election.